Location:

Period:

27 Feb 2010 07:02:04 - 1 Mar 2010 03:53:16 (1 day 20 hours 51 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 7.2; 42 km NNW of Carahue, Chile; (2 Jan 2011) (8km from the swarm center)

5 swarms found nearby.

2010

PS20100227.2(164.7km)

27 Feb

2 days 9 hours

41 earthquakes

PS20100305.2(132.5km)

5 Mar

1 day 5 hours

7 earthquakes

PS20100310.1(182.2km)

10 Mar

6 hours

5 earthquakes

PS20100313.1(147.6km)

13 Mar

17 hours

6 earthquakes

2011

PS20110211.1(164.1km)

11 Feb

5 hours

7 earthquakes

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Seismic Swarm PS20100227.3: February–March 2010 Event Southwest of Cañete, Chile

Seismic swarm PS20100227.3 was recorded 63 km southwest of Cañete, Chile, beginning at 07:02 on 27 February 2010 and concluding at 03:53 on 1 March 2010. Over 44 hours and 51 minutes, the sequence produced 28 earthquakes. Magnitudes ranged from 4.8 to 5.9, with the majority occurring at depths near 35 km and a smaller number at shallower or greater depths between 5 km and 70 km.

The temporal distribution showed the highest activity on the first day, with 11 events recorded by late afternoon on 27 February. The strongest shocks reached magnitude 5.9 at 10:30, 10:38, and 23:02 on 27 February, as well as at 19:48 on 28 February. Subsequent events on 28 February and early 1 March were predominantly in the 5.0–5.3 range, indicating a gradual decline in energy release. Depths remained concentrated around 35 km for most events, consistent with the typical interface depth in this portion of the subduction zone.

This swarm represents the sole seismic swarm documented in the region since 1 January 2000. The only prior comparable cluster also occurred in 2010. A magnitude 7.2 earthquake on 2 January 2011, located 42 km north-northwest of Carahue and approximately 8 km from the swarm centroid, further illustrates the persistent seismic productivity of the immediate area.

The location lies within the central Chile subduction segment, where the Nazca Plate converges with the South American Plate at rates of 6–7 cm per year. This tectonic setting produces frequent megathrust earthquakes and associated aftershock sequences. The 2010 swarm occurred within the rupture area influenced by the great Maule earthquake of 27 February 2010, whose mainshock epicenter was situated nearby. Such swarms commonly reflect stress redistribution along the plate interface and within the overriding crust following large events.

Seismicity in this segment has historically included multiple magnitude 8+ earthquakes over the past two centuries, underscoring the region’s elevated seismic hazard. The 2010–2011 activity aligns with the expected post-megathrust pattern of clustered moderate-magnitude events at intermediate depths along the subduction interface.

References
SeismoSight internal swarm classification PS20100227.3
USGS Earthquake Catalog (events 2010–2011, Chile)
USGS Tectonic Summary: Chile Subduction Zone